Wednesday, 4 July 2012

WHAT CAUSES GLOBAL WARMING?

Global warming
is the rise in temperature of the Earth's atmosphere and oceans. The
causes of global warming have been investigated by scientists for many years,
and research is still ongoing amidst much debate.

Natural cycles and events influence the climate,
but they cannot explain all the changes that are occurring. However, when
additional greenhouse gases produced by man are considered we get a clearer
picture of what is happening. The release of greenhouse gases, through
both natural and man made activities, are responsible for warming the earth and
causing global warming.

Natural causes

The Earth naturally cycles through patterns of
warming and cooling. There are many natural things that contribute to
global warming but natural process occur in a slow and measured way over many
millennia.

There are natural carbon sinks on earth which have been storing
carbon over many thousands of years. These include peat bogs and the
arctic tundra. If warming temperatures cause these carbon sinks
destabilise then carbon will be released into the atmosphere and can possibly
cause an unstoppable catastrophic warming of the earth.

Man made causes

We are accelerating the natural climatological
cycles by releasing man made greenhouse gases into the environment. There
are several greenhouse gases responsible for global warming that are produced
by man. Most are produced by the burning of fossil fuels in factories,
electricity production and use of cars. Carbon dioxide is the main gas
responsible for global warming, but methane, nitrous oxide and refrigeration
gases also contribute.

The build up of carbon dioxide in the environment
is by far the biggest contributor to global warming, resulting mainly from the
use of fossil fuels. The loss of forests also reduces the amount of carbon
dioxide absorbed in the environment and so contribute to increased levels. As forests and grasslands are cleared, enormous
amounts of stored carbon are released from the decaying plants and enter the
atmosphere.

Methane is released from landfill sites and
agriculture (grazing animals produce methane as part of their digestive
process). Nitrous oxide comes from from fertiliser, gases for
refrigeration and industrial processes.

These different gases have varying heat trapping
abilities. A molecule of methane can trap 20 times more heat than a
molecule of carbon dioxide. Nitrous oxide can trap 300 times more heat than
carbon dioxide. Chlorofluorocarbons have heat trapping potential a
thousand times greater than CO2. However CO2 is the greatest contributor
to global warming due to high concentrations.

In order to measure these gases simply, Greenhouse gases are
measured in terms of the equivalent amount of carbon dioxide.